Parallel-flow reactance-coil.



J. F. PETERS.

PARALLEL FLOW REACTANCE COIL.

APPLICATION FILED SEPT. 10, 1914.

1,295,921 Patented Mar. 4,1919.

2 SHE EE WITNESSES: L INVENTOR Jag/7 Pen /5 ATTORNEY J. F. PETERS.

PARALLEL FLOW REACTANCE COIL.

APPLICATION FILED SEPT. 10. 1914.

, 1 ,295,921 Patented Mar. 4, 1919..

2 SHEETS-SHEET 2.

24 23 m i H 1 ILIIIIIII L F 1' I I L' i E l l i; WWHNESSES: INVENTOR MJM fafi/g F/ afars ATTORNEY UNITED STATES PATEN OFFICE.

JOHN F. PETERS, 0F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

PARALLEL-FLOW BEACTANCE-COIL.

Specification of Letters Patent.

Patented Mar. 4, 1919.

Application filed September 10, 1914. Serial No. 861,041.

To all whom it may concern:

Be it known that I, JOHN F. PETERS, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Parallel-Flow Reactance-Coils, of which the following is a specification.

My invention relates to current-limiting reactance devicesand more particularly to improvements in current-limiting reactance coils which are inserted in power circuits as protective means for the electrical apparatus associated therewith.

My invention has special reference to current-limiting reactance coils that are adapted for use in large-capacity power circuits which are traversed by currents of high value.

In power systems, it is of the utmost 1mportance that the service to be rendered be uninterrupted, and that the power-generating apparatus be protected against all short circuits, disturbances, etc:,' in order to insure reliability of operation. 'With the development of high-power generating stations and the large-capacity units embodied therein, it is particularly desirable to protect the electrical apparatus from severe strains caused by short circuits and to limit the possible local concentrations of power at such occurrences.

It is highly desirable that the internal losses of power-limiting reactance coils be minimized in order to insure efficient operation of the associated electrical system. To this end, I propose a reactance coil comprising a plurality of spaced copper strands which are connected in multiple to furnish adequate cross sectional area to conduct the load currents. In order to further reduce the internal losses, the several copper strands are so transposed with respect to each other as to reduce the induced currents or internal circulating currents therein. By spacing the copper strands from one another, the heat-radiating capacity of the coil is greatly increased, thereby permitting each strand to be worked at a considerably higher current density than is usually deemed advisable.

' Because of the large diameter of, and the difliculty involved in winding a single coil comprising an unduly large numberof parallel copper strands, I utilize a plurality of coil sections, each of which comprises a limited number of copper strands. 1 These coil sections are so positioned with respect to one another as to minimize the floor area required for the installation of the complete reactance coil. Again, the difliculty of wlnding a coil section is considerably less than that of winding a coil comprising an unduly large number of parallel copper strands, thereby insuring a substantial -decrease in the cost of labor. Moreover, the impedance offered to short-circuit currents by my present reactance coil is considerable, by reason of the disposition of the several sectlons in mutual inductive relationship. In this manner, the magnetic flux, which is responsible for the impedance oflered to short-circuit currents by its related sections, is utilized to induce impedance Volta es in the other sections mutually inductive y related thereto.

In order to understand my invention more clearly, reference may be had to the following escription and the accompanying drawings in which Figure 1 is a view, mainly in elevation, but partially in section, of a reactance coil constructed-in accordance with my invention; Fig. 2 is a plan view of the coil shown in Fig. 1; Fig. 3 is a diagrammatic representation of my reactance coil; Fig. 4 is an enlargedview, showing the method of interconnecting the coil sections embodied in the coil shown in Fig. 1, and Fig. 5 is an enlarged detail View, partially in section, showing the manner in which a plurality of copper strands, such as are used in building and winding my reactance coil, may be connected.

Referring to Figs. 1 and 2, a plurality of coil sections 1 and 2, each comprising a group of flat spirals 3, are superposed upon each other, substantially as shown in Fig. 1. Radially extending cleats 4, provided with recesses 5 formed on oneface thereof, receive copper strands or conductors 6. The cleats 4: brace the coil against internal mechanical stresses that are set up when heavy short-circuit currents flow through the coil and they also space the various convolutions or turns of the spirals from one another, thereby greatly increasing the heat-radiating capacity of the coil. Longitudinally extending tie bolts 7, projecting through openings in the extremities of the cleats 4, hold the coil layers in fixed relation to one another and brace the spirals against exterml mutual stresses. Insulated supports 8,

comprising porcelain insulators 9 and metallic feet 10 associ'aited therewith, prevent the coil from grounding on the bed plate or floor upon which it may be disposed. Conducting rods 11 and 12, dlsposed 1n the opening of the coil and extending parallel to its axis, serve as terminals for the COll. By means of members 13 and 14, which are mounted on the conducting rod 11, it is possible to make electrical connections with the coil at either the top or the bottom. The conducting rods 11 and 12 engage Spreaders, shown as Y shaped spreaders 15, which are disposed at the top and the bottom of the coil and brace it against any mechanlcal forces to which it may be sub ected.

Inasmuch as it is desirable that the powerlimiting reactance coil offer a minimum reactance to the normal load current and considerable reactance to short-circuit or abnormally large currents, it is usual to provide a non-magnetizable core for the; 0011. An air core or a core of a non-magnetizable material which will impart a. straight-line characteristic to the coil is usually preferred.

' Under certain conditions, it may be more economical to supply an iron core for a reactance coil of high impedance. However, I prefer to use air cores, when possible, and have shown my structure so provided. The air core greatly assists in ventilating the coil and in rapidly dissipating the generated heat, in addition to substantially decreasing the total weight of the coil.

As above mentioned, my reactance coil is designed to be utilized in circuits over which large currents flow. Under such conditions, a reasonable number of parallel copper strands would not suifice to carry the load currents unless each strand was of a cumbersome and undesirable diameter. To avoid such condition, I utilize a plurality of coil sections which are connected in multiple, each section comprising a reasonable number of parallel copper strands. In this way, the coil may be cheaply and easily wound.

In order to lend clearness to the drawings and to illustrate my invention in a simple manner, I have shown each coil section 1 and 2 as composed of three parallel copper strands 16, 17 and 18, but it will be understood that, in practice, a larger number of copper strands, as, for instance, seven, eight, nine or more, will usually be employed. Of course the number of the parallel copper strands does not affect the novelty of my invention.

I prefer that the coils be wound by the method disclosed in U. S. Patent No. 1,241,549, issued to Westinghouse Electric & Manufacturing Company, Oct. 2, 1917, on an application filed by myself. That is conductor 16, extending from the binding post 11, engages the inner- I 17 engages the second recess, while the conductor 18 engages the innermost recess. The three conductors 16, 17 and 18 continue to engage the corresponding recesses in the next two bars 4, but, on arriving at the initial bar 4, the conductor 18 is stepped outwardly to the second recess, the conductor 17 to the third recess, and the conductor 12 to the fourth recess, the innermost or first recess having been previously engaged by the conductor 16 at the beginning of the operation.

As the winding operation is continued and the first layer is nearing completion, the conductor 16, after it engages the outermost recess in the bar 4, is stepped downwardly to engage the corresponding recess in the second layer or series of bars 4, which layer is immediately adjacent to the top layer. Similarly, the conductors 17 and 18 successively occupy the outermost notches in the proper radial bar 4 of the secondlayer and, all of the conductors are wound to progress inwardly toward the center of the coil.

When this coil layer is completed, the conductors are stepped to a third layer in which they arewOund similarly'to the first layer. In employing this method of winding, the copper strands-comprising the coil sections are so wound that they all have substantially the same length and impedance in order to entirely eliminate internal circulating currents. The efficiency of the coil is thus greatly increased, by reason of the substantial elimination of internal losses.

Referring to Fig. 3, the relationship between the coil sections 1' and 2 and the direction of the current flow therethrough are illustrated. Leads 19 and 20, each of which represents the three copperstrands 16, 17 and 18, are connected together to constitute the terminal 11. Leads 21 and 22, representing the same copper strands, are connected together to constitute the terminal 12 by the clamping means to be described in connection with Figs. 4 and 5.

In building up the coil, the lower section 2 is first wound by operating the winding machine or lathe in one direction. The lead 20 of Fig. 3 constitutes the starting lead and the lead 22 constitutes the finish lead when winding the coil section 2. A conductor comprising this coil section may be traced terminal 20 to the terminal 22. Likewise, the current is directed throu h this coil section in a counter-clockwise irection, as indicated by the arrows. After the section 2 is completely wound, the up er section 1 is wound by operating the win ing machine in the reverse direction. The lead 21 constitutes the starting lead. and the lead 19 the finish lead when winding the coil section 1. A conductor comprising this coil section may be traced in a clockwise direction from the terminal 21 to the terminal 19. The current, however, is directed through this coil section in a counter-clockwise direction, as indicated by the arrows. The finish leads 22 of the lower section 2 and start leads 21" of the upper sectionl, being ad acently disposed midway between the ends of the re-' actance coil, are then connected together to constitute the terminal 12. As a result, the two coil sections do not need to be insulated from each other, as would be the case if said sections were wound in the same direction and the start leads or finish leads of both sections were connected together. Start or lower leads 20 of the lower section 2 are connected to finish or upper leads lQf ofthe upper section 1 to constitute the terminal 11. The arrows in Fig. 3 indlcate that the current fiows in both coilsections in such a direction that they are positively and mutually inductively related, and, inasmuch as the sections are so wound as to have equal impedances, equal quantities of current Wlll flow through them. As a result, the magnetic fluxes induced in the coil sections are additive and will flow in thesame direction through them. Therefore, the impedance of each coil section results from its own induction and the induction imparted by the other section. Consequently, the total impedance ofi'ered by the coil will be greater than the impedance offered by two separate coils so disposed as not to be positively and mutually inductively related to each other.

lVhile I have shown and described a reactance coil comprising two superposed sections which are connected in parallel relationship and so constituted as to take equal quantities of load current, it will be nnderstoodthat any number of coil sections may be utilized which will insure adequate cross sectional area of the copper strands for conducting normal currents.

In Figs. 4 and 5, I have illustrated a device by means of which the conductors constituting the terminal 12 may be connected together. For the purpose of illustration, I have shown fourteen parallel conductors which represent. the copper strands employed building up one of the reactance coils. The seven copper strands constituting the upper coil section, in connection with the seven copper strands constituting the lower coil section, embrace the central rod 23 upon which they are circumferentlally disposed, as shown in Fig. 5. The rod 23 embraced by the copper strands constitutes the portion of the terminal 12 which is disposed within the coil opening. All of the copper strands meet at adjacent points 23 of the coil which in this particular instance, are disposed midway between the ends of the coil, as shown in Fig. 1. Clamps 24, which embrace the fourteen conductors and the central rod 23, are spaced from one another and along the rod 23 to hold the copper strands securely in fixed relationship to one another. Each clamp 24 comprises two segments 25 and 26, each of whlch is provided with an extending portlon 27 and lugs 28 which admit of insertion of bolts 29. It will be seen that the segments 25 and-26 are electrically insulated from each other by an insulating washer 30 which embraces a tie bolt 29*. This structure prevents the formation of eddy currents and consequently, keeps the internal losses within the coil down to a very small value.

While I have herein shown and described a preferred embodiment of my invention, it will be understood by those skilled in the art, that various modifications may be made without departing from the spirit and scope of my invention, and I desire that only such limitations shall be imposed as'are indicated in the appended claims.

I claim as my invention 1; A current-limiting reactance coil comprising a plurality of superposed coilsections which are positively and mutually inductively related and oppositely wound, each section being composed of a plurality of fiat parallel spirals and the corresponding leads of the sections being connected in multiple to constitute terminals for the coil.

2. A current-limitingreactance coil comprising two superposed coil-sections which are mutually inductively related, each section being composed of a plurality of parallel conductors wound to form a series of flat parallel spirals, the lower leads of the lower section being connected to the upper leads of the upper section and the upper leads of the lower section being connected to the lower leads of the upper section to constitute coil terminals.

3. A current-limiting reactance coil comprising two superposed and parallel'connected coil sections which are positively and mutually inductively related and reversely wound, each coil section being composed of conductors wound to form a series of spirals.

4:. A current-limiting reactance coil comprising two super-posed coil sections which are connected in multiple and are positively and mutually inductively related and reversely wound, each coil section being composed of a plurality of parallel-connected and spaced conductors wound to form a series of fiat parallel spirals.

5. A current-limiting reactance coil comprising tw'o superposed coil sections which are mutually and inductively related and reversely wound, both coil sections being composed of conductors wound to form a series of flat parallel s ira'ls, one terminal of the coil comprising t lie leads of sections which terminate midway between the coil ends, and the other terminal of the coil comprising leads of the sections which terminate at the coil ends.

6. A current-limiting reactance coil comprising two' superposed coil sections which are positively and mutually inductively related, both coil sections being composed of conductors wound to form a series of 'flat parallel spirals, one terminal of the coil comprising the leads of the sections which terminate midway between the coil ends and the other terminal of the coil comprising leads of the sections which terminates at the coil ends.

7. A current-llmltlng device. comprlslng a .plurality of coil-sections positioned in mutual inductive relationship, each of said ing-current fluxes in the same direction to increase the inductance of each separate coil-section over that inherently possessed.

9. A current-limiting device comprising relationship and for. so directing the currents flowing therethrough that the total inductance of said device exceeds the inductance of the separate coil-sections.

10. A current-limiting reactance coil comprising a plurality of separate coil-sections,

and a connecting device for directing the current flow through said separate sections, said device comprising a central rod, 9. plurality of electric conductors circumferentially and longitudinally disposed thereupon, segments provided with lugs and extending portions embracing the conductors, bolts cooperatively engagim the lugs to hold said segments in fixed re ationship, and an insulating sleeve embracing one of said bolts to insulate the segments from each other.

11. A current-limiting reactance coil comprising a plurality of separate coil-sections, and a connecting device for directing the current flow through said separate sections, said device comprising a central rod, a plurality of electric conductors, circumferentially and longitudinally disposed thereupon, and clamps embracing the conductors, each clamp comprising segments each of which has one lug disposed at one end and a second lug disposed a short distance from the other end to provide an extension, bolts cooperatively engaging the lugs to hold the segments in fixed relationship, and an insu lating sleeve embracing one of said bolts to insulate the segments from each other.

In testimony whereof, I have hereunto subscribed my name this 25th day of Aug,

JOHN F. PETERS. Witnesses:

H. FAHNOE, B. B. HINES. 

